1. Field of the Invention
The present invention relates to an optical module for use in optical communications. More particularly, the present invention relates to an optical module which can be locked in a cage for accommodating the case of the optical module.
2. Description of the Related Art
Conventionally known optical modules for use in optical communications include an optical transceiver which comprises a light emitting element and a light receiving element for performing opto-electric conversion to make communications through optical fibers.
One type of such optical transceivers comprises an optical unit, including a light emitting element and a light receiving element, which is contained in a case, and is structured for removable accommodation in a cage mounted on a substrate. The case has an electric connector connected to the substrate, such that the optical transceiver plugged into the case causes its connection terminals to come into connection with the electric connector of the cage. The optical transceiver thus constructed converts an optical signal communicated to/from an optical fiber to an electric signal communicated to/from the substrate, and vice versa to enable optical communications.
However, if an optical transceiver is withdrawn from the cage during the operation of the optical transceiver, a communication device including the optical transceiver can fail, needless to say that a communication is interrupted in the middle. For this reason, the optical transceiver must be securely fixed within the cage at least during its operation.
In recent years, an industrial standardization organization has developed a standard called MSA (MultiSource Agreement) for SFP (Small Form-factor Pluggable) transceiver, by way of example, for making optical transceivers provided from respective companies compatible with one another. MSA defines the shape and dimensions of SFP transceivers and cages for accommodating the SFP transceivers. According to the SFP MSA standard, a protrusive latch is formed on the bottom surface of an optical transceiver, while a cage is provided with a spring plate formed with a retaining hole for retaining the latch therein, so that when the optical transceiver is inserted into the cage, the latch of the optical transceiver can fit into the retaining hole of the cage to lock the optical transceiver to the cage. On the other hand, for removing the optical transceiver from the cage, any means must be used to release the latch from the retaining hole of the spring plate to unlock the optical transceiver from the cage.
FIG. 1 is a perspective view illustrating a conventional optical transceiver disclosed in U.S. Pat. No. 6,434,015, with its bottom surface oriented upward.
The conventional optical transceiver illustrated in FIG. 1 comprises housing 101 for accommodating a light emitting element and a light receiving element and formed with latch 114; and ejector 170 for removing latch 14 from a retaining hole (not shown) of a cage. Ejector 170 is arranged in an ejector sheet formed in lower portion 111 of housing 101, such that depression onto push plate 179 arranged at the rear end of ejector 170 enables the leading end of ejector 170 to extend to the vicinity of latch 114 from within the ejector sheet. When the leading end of ejector 170 is protruded while latch 114 of the optical transceiver is retained in the retaining hole of the spring plate of the cage, the spring plate is bent to release latch 114 from the retention by the retaining hole.
Thus, this optical transceiver can be withdrawn from the case by pushing push plate 179 of ejector 170 in a direction indicated by an arrow A in FIG. 1 to protrude the leading end thereof to the vicinity of latch 114, and releasing latch 114 from the retention by the retaining hole formed through the spring plate of the cage.
However, An SFP optical transceiver conforming to the MSA standard should have a height of about 10 mm and a width of about 14 mm, i.e., the SFP optical transceiver itself is small in size, so that ejector 170 (see FIG. 1) disposed in such a small optical transceiver must be a miniature part. For this reason, it must be a finger tip (or a nail tip in some cases) that should depress push plate 179 of ejector 170 illustrated in FIG. 1. However, there is few clearance between the substrate on which the cage is mounted and the bottom surface of the optical transceiver, when the optical transceiver is mounted in the cage, so that the finger tip may not successfully reach the push plate 179 of ejector 170, thus experiencing difficulties in performing operations for unlocking the optical transceiver from the cage.
Also, the optical transceiver illustrated in FIG. 1 is withdrawn from the cage in a direction indicated by arrow B, which is opposite to the direction (the direction indicated by arrow A) into which ejector 170 is pushed. In other words, the conventional optical transceiver involves the unlocking operation and the removal of the optical transceiver from the cage in the direction opposite to each other, so that these operations must be performed independently of each other. Eventually, this optical transceiver disadvantageously entails a long time and many manipulations for removing the optical transceiver from the gage after the optical transceiver has been unlocked.